1. Field of the Invention
The present invention relates to a portable wireless terminal, a wireless terminal, a wireless communication system, and a wireless communication method.
2. Description of the Related Art
All patents, patent applications, patent publications, scientific articles, and the like, which will hereinafter be cited or identified in the present application, will hereby be incorporated by reference in their entirety in order to describe more fully the state of the art to which the present invention pertains.
Conventionally, medical diagnosis using an endoscope in the medical field has been performed. An image capturing element such as a charge coupled device (CCD) is embedded in the head of an insertion part of an endoscope scope (hereinafter referred to as a scope), and a processor performs signal processing with respect to an image capturing signal photographed by the CCD, so that it is possible to observe an image (an endoscope image) of an inside of a body through a monitor. Normally, the scope and the processor are connected to each other using a signal cable.
Meanwhile, a wireless endoscope system in which the scope and the processor are connected to each other in a wireless manner has been proposed. In the wireless endoscope system, a limitation of an operation using a signal cable is reduced, resulting in the improvement of operability. Furthermore, in an electronic endoscope system in which the scope and the processor are connected to each other using a signal cable, it is necessary to isolate the scope from the processor in order to ensure stability. However, in the wireless endoscope system, since a wireless connection is established instead of an electrical connection, a configuration for the isolation is not necessary. However, in the wireless endoscope system, in order to perform reliable data communication between the processor and a plurality of wireless endoscopes or between the processor and other wireless communication devices, it is necessary to consider interference caused by wireless communication.
As a countermeasure thereto, in general, an autonomous distributed wireless terminal checks a peripheral radio wave state before starting communication, selects a channel less affected by interference, and starts communication. For example, an electronic endoscope system has been known in which a processor regularly receives a report of a channel used from a scope operating nearby, stores information on the channel used, automatically assigns an unused channel when a channel assignment request signal has been received from a target scope, and uses the unused channel as a channel for the scope (for example, refer to Japanese Unexamined Patent Application, First Publication, No. 2006-271432, which will be referred to as patent document 1).
In the technology disclosed in patent document 1, after a channel to be used for image transmission between the processor and the scope is set, it is not possible to change the channel. Therefore, after the channel to be used for image transmission is set once, even when a communication state of the channel set based on a peripheral radio wave condition and the like is deteriorated, communication should be continued through the channel.
The present invention provides a portable wireless terminal, a wireless terminal, a wireless communication system, and a wireless communication method, by which, even after a channel to be used for communication between wireless terminals is set, it is possible to change the channel to be used for communication between the wireless terminals.